This invention relates to an electrical connector and more particularly to a low insertion force connector having a contact arrangement that provides good electrical contact while eliminating the wiping action normally experienced with printed circuit card insertion.
In many systems and for a variety of reasons, many electronic elements, components, circuitry, and interconnections are presently mounted, deposited, printed, or otherwise formed on one or both sides of a printed circuit board or other suitable substrate. Electrical interconnections between connectors are generally made to a backpanel. That is, the connector is inserted onto one surface of a backpanel with the connector leads extending through the backpanel, the wires forming the interconnects are then wire-wrapped around the extended conductors. The printed circuit board is then inserted into the connector on the backpanel. The connectors generally include a housing or base which is bolted or otherwise affixed to the backpanel and the housing is formed with a longitudinal slot for receiving one edge of the printed circuit board. Connections between the connector conductors and the corresponding edge contacts on the printed circuit board are generally made by mechanically biasing the connector conductors into engagement with the edge contacts of the printed circuit board. The mechanical biasing force serves two purposes, the first being to provide solid electrical connections and the second being to provide a grip on the printed circuit board so as to hold the printed circuit board in the connector. The biasing force must be relatively high to ensure that good conductive contacts are made and maintained. The high biasing force in turn causes a high insertion force which becomes excessive when the number of connector conductors is large. Any friction force on the printed circuit board edge contacts, causes a rubbing which removes the surface material. Since the edge contacts are only a few thousandths of an inch thick and generally gold-plated, this rubbing action will remove the high quality conductance surface and invite poor electrical contact and/or corrosion.
One solution to the insertion problem is the mechanical actuating mechanism that removes the biasing force during the insertion and removal of the printed circuit board. Such a mechanism is more specifically shown in U.S. Pat. No. 4,189,199, entitled, Electrical Socket Connector Construction by T. G. Grau. In that patent there is disclosed an actuating mechanism which is activated by the insertion of an integrated circuit pack causing the connector conductors to move into contact with the pins of the integrated circuit pack.
In summary of the prior art, zero insertion connectors eliminate the rubbing action by physically displacing the connector contacts from the edge contacts during insertion and removal of the printed circuit board.
The inventor of the present invention, Warren W. Porter, conceived of a low insertion force connector which is shown in U.S. Pat. No. 4,355,856, entitled Low Insertion Force Connector Using Non-Noble Metal Contact Plating, issued on Oct. 26, 1982. The connector of the referenced application utilizes electrically conductive pins which engage a printed circuit board as it is inserted into the connector. The engagement occurs at one end of the electrically conductive pins such that the point of contact with the circuit board is maintained and the electrical contact pin is rotated so as to follow the path of the printed circuit board into the connector. A biasing means pressing onto the opposite end of the electrically conductive pins maintains the pins in electrical contact with the edge contacts of the printed circuit board. Rubbing between the card contacts and connector conductors is thus eliminated. The connector of the referenced application is concerned with a printed circuit board having electrical contacts only on one end and wherein the board is inserted transverse to the longitudinal axis of the connector.